An acquaintance or friend who tends to disappear into thin air. Often a member of a group of friends who tends to bail at parties, leave early during an engagement, or otherwise is notorious for fleeing the scene without duly giving notice.
"Man, this party is just starting to warm up, but I can't find Peter. I bet Peter pulled a Ghost Dawg again."
"So the new employee just walked off the job? Just like that, without even alerting anybody? He pulled a Ghost Dawg."